Automatic pipe cutting apparatus



1968 MICHIO HIRATSUKA ETAL 3,362,699

AUTOMATIC PIPE CUTTING APPARATUS Filed Feb. 21, 1964 5 Sheets-Sheet 1FIG. I"

\A SELSYN RECEIVER CUTTING SPEED SETTER DETECTING T DEVICE ACONTROLCIRCUIT VARIABLE RANSDUCER RESISTANCE 2 SLIDE i [RESISTANCE 'SLIDF VVARIABLE RESISTANCE RES'STANCE INVENTOR. hk uo \rmyJQ BY Ymcki TAakA-bskm 2L MAM 1968 MICHIO HIRATSUKA ETAL 3,362,699

AUTOMATIC PIPE CUTTING APPARATUS Filed Feb. 21, 1964 5 Sheets-Sheet 2FIG.2 FIG.3

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mesh in. mesh United States Patent 2 Claims. 61. 266-23) This inventionrelates to a pipe cutting apparatus and more particularly to a pipecutting apparatus for accurately and automatically working or cuttingthe ends of a branch pipe or an opening for joining a branch pipe in theconfiguration of the joint portion so as to ensure positive weldingbetween pipes to be joined in the case of branching off a branch pipefrom a pipe line such, for example, as a stress member of a building ofpipe structure or a pipe line for liquid transport.

In order to join a branch pipe to a pipe there will be required acutting operation for cutting oif an end of the branch pipe in theconfiguration of the joint line and another cutting operation for makingan opening on the side of the pipe to which a branch pipe is to bejoined in the configuration of the joint line.

Heretofore, in a pipe cutting apparatus for such operations, therotation of the pipe and the movement of a gas torch were jointlycontrolled by means of a complicated crank arm, resulting in suchdrawbacks as complicated setting procedures to meet various conditions,as well as the possibility of errors due to mechanical joints.

An object of this invention is to provide a supporting device forsupporting and rotating a pipe to be subjected to cutting operations anda cutter which moves on the center line of the pipe side along the axialline of the pipe, wherein an electrical operation is performed so thatthe position of said cutter can move along the joint line correspondingto the rotation of said pipe so as to effect automatic control by meansof said electrical operational output.

The features of the invention which are believed to be novel are setforth with particularity in the appended claims. The invention itself,however, as to principle together with organization and advantagesthereof may best be understood by reference to the following descriptiontaken in connection with the accompanying drawings, in which the likeparts or members are designated by like reference characters, and inwhich:

FIG. 1 is a schematic diagram showing an embodiment of this invention;

FIG. 2 is a top view showing the cutter portion of the apparatus of theinvention in the case of cutting off a pipe end;

FIG. 3 is a top view showing the cutter portion in the case of cutting apipe opening;

FIG. 4 is an illustration of a cutting-off line in the case of joining apipe to another pipe of larger diameter;

FIG. 5 is an illustration of a cutting-oil line in the case of joining apipe to a fiat plane;

FIG. 6 is an illustration of an opening cutting line in the case ofjoining a pipe to a pipe of small diameter; and

FIG. 7 is a schematic view illustrating the cutting speed.

As shown in FIG. 1, a pipe 1 to be worked is supported by a chuck of asupporting means 2 and is caused to rotate by a motor M through a gear3. A detecting means 4 is provided for detecting the rotational angle wtof the pipe 1 (where w is the angular velocity of the pipe and t is therotating time; although it is actually "ice it is represented herein bywt). At the side of the pipe 1 there is provided a cutting means, suchas, for example, a gas torch or a cutter 5 (refer FIG. 3) which issupported by a supporting means 6, which is caused to move in the axialdirection of the pipe 1 by a servo-motor M through a gear mechanism 7and a feed screw 8 with which the portion of the supporting means 6 isengaged. A detecting means 9 is provided to detect the position of thecutting means 5, while a transducing means 10 is provided forelectrically transducing the detected value of the said detecting means9. An operation circuit C performs electrical operation according tosaid rotation angle wt, the radius r of the pipe 1 to be worked, theradius R of the pipe to be joined with said pipe 1, and thecomplementary angle 0 of the joint angle between said pipe 1 and saidpipe to be joined thereto. An amplifier A is provided to control theservo-motor M in accordance with the output voltage of the saidoperation circuit C and the output voltage from the transducing means10. There are also provided a knob 11 for switching either to thecutting off of a pipe end or to the opening of a pipe, a knob 12 forsetting the radius r of a branch pipe, a knob 13 for setting the radiusR of a pipe to which a branch pipe is to be joined, a knob 14 forsetting the complementary angle 0 of the joining angle, and a knob 15for setting the cutting speed, together with amplifiers A A and Aservo-motors M and M and a cutting speed setter D.

First, as shown in FIG. 4 a case wherein a pipe 1 with a radius of R isjoined to another pipe 1 with a radius of r (Where Rgr) at a joint angle5 will be explained. In this case, it is necessary that the pipe 1 to beworked having a radius of r be cut oil along the joint line thereof intothe form indicated by a thick line in the drawing. Therefore, the amountx of displacement of the cutter 5 from a point 0 with the rotationalangle of the pipe 1 at wt can be represented by the following equation:

Hence, when the knob 11 is set on its cut off side, and the slidingelement of a potential divider VR connected to a constant voltage E isset so as to correspond to the radius r, a voltage corresponding to theradius r can be obtained as its output voltage. If the output voltage isadded to a non-linear slide resistor P2 whose resistance variessinusoidally and the sliding element of said nonlinear slide resistor Pis caused to vary according to the rotational angle wt of the pipe 1which can be detected by means of the detecting means 4, the outputvoltage will be in proportion to r sin wt. Therefore, by impressing thisoutput voltage to a non-linear slide resistor P whose resistance variessinusoidally and the sliding element of the said non-linear slideresistor P is set by a knob 14 in accordance with the complementaryangle 0 of the joint angle 6, the terminal voltage V thereof will be inproportion to r sin wt tan 0 When the sliding element of anotherpotential divider VR connected to the constant voltage E is set by aknob 13 according to the radius R of the other pipe 1,, the outputvoltage is added to a non-linear slide resistor P whose resistancevaries sinusoidally, and the sliding element of said resistor is causedto rotate by means of the servomotor M an output voltage proportional toR sin a can be obtained according to the rotation angle at of saidservomotor M When this output voltage is impressed on a non-linear slideresistor P Whose resistance varies sinusoidally and the sliding elementthereof is set according to the complementary angle of the joint angle,the output voltage V obtained is R sin a cos 0 Further, when the outputof a potential divider VR by which a voltage corresponding to the radiusr of the pipe 1 is obtained, is added to a non-linear slide resistor Pwhose resistance varies consinusoidally, and the sliding element of saidresistor P is caused to vary together with the sliding element of theslide resistor P according to the rotational angle 0.12 of the pipe 1,the output voltage of the non-linear slide resistor P will be inproportion to 1 cos wt. Also, when the output voltage of the potentialdivider VR said voltage corresponding to the radius R of the pipe 1,,,is added to a non-linear slide resistance R; whose resistance variesconsinusoidally, and the sliding element of said resistor R; is causedto rotate together with the sliding element of the slide resistor P bymeans of the servomotor M an output voltage proportional to R cos oz isobtained according to the rotational angle a thereof. When thedifference voltage between the output voltage R cos 0: of the non-linearslide resistor P and the output voltage r cos of of the non-linear slideresistor P is amplified by the amplifier A thereby driving theservomotor M and controlling the position of the sliding elements of thenon-linear slide resistor P and P so that said difference voltagebecomes 0, there will be always established the following relationshipprovided that the responsive characteristic of the servomotor M issufficiently good.

R cos oz=r cos wt Therefore, the output voltage R sin a. of thenon-linear slide resistor P which is interlocked with the non-linearslide resistor P can be expressed by Hence, the output voltage Vexpressed by the Equation 3 can be written as follows;

1 2 2 2 x R r cos wt is obtained, thereby making it possible to obtainan operational output that coincides with the value of X in Equation 1.

Thus, the function of the rotational angle oz of one of the pipes is setcorresponding to the function of the rotational angle wt of the otherpipe by an electrical servocircuit, and the required joint line isconverted into a function of a distance in the axial direction whichcorresponds to the rotational angle of the pipe to be worked by means ofan electric operational mechanism provided with said circuit andincluding the diameters of each of said pipes and the joint angle as theoperational factors. Then it becomes possible to control the position ofthe cutter 5 through an amplifier A by the dilference between the outputvoltage of the operational mechanism which is a combination of saidelectrical elements and the output voltage of the converting means whichis produced in accordance with the actual position of the cutterdetected by the detecting means 9, whereby the position of the cutter 5can be caused to coincide with Equation 1 so as to cause it to travelalong the required joint line as shown in FIG. 4, thus accomplishingcutting in the manner desired.

The non-linear slide resistor P whose resistance varies sinusoidally canbe so arranged that the output voltage is increased by K times bywinding sparsely or densely the resistance windings in such a mannerthat each resistance value for a displacement angle 0 with respect tothe total resistance value Z becomes, for example:

(where K is a constant) The above constant K may be selected dependingupon the ratio of the value of output voltage at the maximumdisplacement angle 0 established to the output voltage at an angle of45.

Furthermore, a nonlinear slide resistance P whose resistance valuevaries as a secant function can be obtained, for example, by obtaining acoeflicient K which corresponds to the resistance value at the requiredmaximum displacement angle, making one part Z/K of the total resistancevalue Z a fixed resistance and the other part variable by means of asliding element, and winding the resistor with varying density so thatthe resistance value for each displacement angle 9 becomes,

Z =-sec 0 1&2 thus amplifying the output voltage by K times.

In the case of joining a pipe 1 which is to be a branch pipe to a flatsurface with an appropriate joint angle 6, it is necessary that thejoint line of the pipe that is to be a branch pipe be formed as shown bya thick line in FIG. 5. Therefore, the displacement X of the cutter S,with the rotational angle of the pipe 1 at wt, from the point 0 can beexpressed by X=r-sin wt tan!) where r is the radius of the pipe 1 and 0is the complementary angle of the joint angle 5. That is, the pipe 1 canbe cut off as shown in FIG. 5 by controlling the position of the cutter5 according to an output value which can be obtained by operating thegiven radius r of the pipe, the complementary angle 0 of the joint angle6, and the rotation angle wt of the pipe which is obtainable from thedetecting means 4 so as to cause coincidence with the above Equation 5.

As described in the explanation for Equation 2, the output voltage V ofthe non-linear slide resistor P coincides with the value of Equation 5.Therefore, the operational circuit in the case of cutting off the end ofa pipe to be joined to a flat surface can be composed of only thepotential divider VR and the non-linear slide resistors P and PMoreover, in the embodiment shown in FIG. 1, it may be assumed that theradius R of the pipe 1 to be joined to the pipe 1 has become infinitelygreat. Hence, when the set value of the knob 13 is at 0, the outputvoltage V of the non-linear slide resistor P becomes 0, whereby thenecessary operational output can be obtained.

Next, the work of opening a joint hole to be provided on a pipe which isto be joined to a branch pipe will be explained.

Referring to FIG. 6, when a pipe 1,, having a radius R is to be joinedto a branch pipe 1 having a radius r, it is necessary to cause the pipe1 to be opened and cut 05 on the side thereof along the joint line asshown by a thick line in the drawing. Therefore, the displacement X ofthe cutter 5 from the point 0, with the rotation angle of the pipe 1 atwt, will be r 6 sm wt+tan 6 R 1* cos wt wherein: R cos a=r cos w! 5amplifier A; as a result of said switching of the knob 11, whereby thesliding elements of the non-linear slide resistors P and P are caused bythe resulting rotation angle wt to vary. As explained before, since acondition expressed by R cos a=r cos wt has been satisfied by anelectrical automatic servo-circuit comprising the amplifier A2 andservomotor M3. The output voltage of the potential divider VR is avoltage corresponding to r, the output voltage of the nonlinear resistorP is impressed into the amplifier A as the input corresponding to r coswt, and the output voltage of the nonlinear resistor P corresponds to rsin wt. The ltasrt-mentioned voltage (of the resistor P is impressedinto the nonlinear resistor P by switching the knob 11, whereby theoutput voltage of the nonlinear resistor P the voltage of which is Vbecomes l 1 sm to t cos On the other hand, the output voltage of thepotential divider VR is a voltage corresponding to R, the output voltageof the nonlinear resistor P is impressed into the amplifier A as theinput corresponding to R cos a, and servo-operation is carried out sothat the difference between the said input R cos a and theaforementioned input r cos wt may become a minimum, whereby the outputvoltage of the nonlinear resistor P becomes the value represented by Rsin a, that is,

This voltage is impressed into the nonlinear resistor P by switchingover the knob 11, whereby the output voltage of the nonlinear resistor Pthe voltage of which is V becomes By combining said output voltages Vand V an operational output which coincides with Equation 6 can beobtained. By means of this operational output, the moving position ofthe cutter 5 can be controlled, and necessary opening and cutting can beobtained.

In this case, the reason why the nonlinear resistors P and P are made toslide by means of the motor M is as follows:

Between the radii R and r of the respective pipes 1a and 1, thefollowing relation always necessarily is established Rgr and R cos a=rcos wt In the case of cutting the pipe, as in the embodiment of FIG. 4,the rotation itself of pipe 1 held by the chuck 2 has been obtaineddirectly as the rotational angle wt, but when the pipe 1 in FIG. 6 isheld by the chuck 2 it is impossible to obtain the rotational angle wtof the pipe 1 which abuts upon the pipe 1 (which is worked so as to beperforated) from the chuck 2 because of the fact that in the cast of thecutting aperture of the pipe 1,, a power is not the rotational angle wtof the pipe 1. Consequently, in the case of the cutting aperture of thepipe 1,, a power source for affording the rotational angle wt of thepipe 1 is necessary. For this purpose, a motor M is provided. That is,it is only necessary to adjust the sliding elements of the nonlinearresistor P and P according to the rotational angle wt of the pipe 1 bymeans of said motor M When this rotational angle wt exceeds 21r, similarpursuit of the locus of the aperture of the cut pipe is done as will beclearly understood from the Equation 6. In this case, what motion occursin the pipe 1 held by the chuck 2. The manner of this motion will bedescribed as follows.

When wt=0, then cos wt=l, and the relation R cos a=r is established.Consequently, let it be assumed that the relative position point 100corresponding to the relation is a starting point of rotation of thepipe 1,. In this case, in the course of clockwise rotation of the pipe1,, when the relation (wt=1r/2) is established, the relation (r coswt=0=R cos a) is obtained and the position corresponding to thisrelation becomes a point 200. With further increase of wt, the relation(wt=1r) is established and the relation (cos wt=l) is established. Theposition corresponding to said last relation corresponds to the point300. After the above rotation of the pipe 1,, when the angle wt becomesmgr-2w, the pipe 1,, is reversely rotated counterclockwise in thesequence corresponding to the points 300- 200 100, whereby the pipe 1,,is restored to the position corresponding to the point 100.

In this case, the pipe 1 carries out one rotation corresponding to(wt=0--21r), so that it is intended to afford the angular displacementcorresponding to the rotation of the pipe 1 by means of the motor M Themotor M is made to operate, in accordance with the angular displacementwt given from the motor M so as to carry outelectric servo-operationcorresponding to the relation R cos w=r cos wt whereby the motors M andM are driven so that the Equation 6 may be satisfied.

The explanation on joint lines illustrated in FIGS. 4, 5, and 6describes the examples of joint lines cut and formed according to thisinvention. For example, in the case of joining a pipe 1 with a pipe 1,,with some displacement from the center of the pipe 1,, it is possible,of course, to accomplish the cutting into a required shape by analyzingthe joint line and composing an operational circuit correspondingthereto so that the joint line can be obtained as the combination ofelectrical elements. This can be accomplished, for example, by adding avoltage corresponding to the displacement value to the output voltage ofthe non-linear slide resistor P In the case of joint welding of pipes,in order to form padding in the welds, it is necessary to providebeveling either on the cut end of the pipe 1 which is to be the branchpipe or the cut surface of the opening of the pipe 1 to which the branchpipe is to be attached.

For this purpose, as shown in FIGS. 2 and 3, the cutter 5 is so adaptedthat the fitting angle thereof is made adjustable by a pivot 62 on asupporting arm 61 which is mounted on the supporting means 6. Thesupporting arm 61 is caused to rotate synchronously with the rotationalangle wt of the servomotor M by both a selsyn transmitter S whichgenerates a voltage related to the rotational angle wt of the servomotorM and a selsyn receiver 8; which receives the said voltage. Therefore,when the cutter 5 is directed in the direction of the cutting portion ofthe pipe and the fitting angle 3 with respect to the axial line of thepipe is fixed equal to the joint angle 6, in case of cutting off thepipe to be worked, the direction of the cutter is not changed due to thelack of instruction from the selsyn transmitter, thereby enablingbeveling to be made as required as shown in FIG. 2 over the entireperiphery of the cutting surface due to the rotation of the pipe 1,whereas in the case of cutting an opening, the cutting direction of thecutter 5 with respect to the pipe axis varies in conical form accordingto the rotation of the pipe 1,, thereby enabling beveling as shown inFIG. 3 to be obtained automatically, simultaneously with the cutting.

In the foregoing explanation, the rotational speed of the pipe, that isto say, of the motor M or servomotor M was explained as being caused tobe a constant speed by the cutting speed setter D. In such a case, theactual speed of the cutter 5 is considered to be the vector resultantvalue of the peripheral speed Vy of the pipe 1 and the moving speed Vxof the cutter as shown in FIG. 7. Hence,

7 the cutting speed is liable to fluctuate greatly as a result 7 ofchange in the cutting shape, with the possibility. o unevenness incutting.

As a countenneasure, it is possible to maintain the actual cutting speedof the cutter 5 always at a' constant rate byproviding a detecting meansB for detecting the moving speed Vx of the cutter 5 and by applying theout put voltage thereof and the cutting speed setting voltage Vcestablished by-a cutting speed setter 1D to a control circuit F, therebyextracting the output voltage of Ve -Vac and using it to rotate themotor M or the servomotor M480 as to reduce'th'e rotational speed of thepipe when the moving speed Vxof the c-utter increases. 1

Thus, according to this invention, in cutting and work ing pipes alongtheir joint line, said pipes to be joinedlat an appropriate joint angle,a supportingmeans for supporting the pipe to be cut and wor lrecl andfor rotating the same and a'cutter which moves onthe center line of theside of the pipe along-the axial-lineof the pipe are provided, and anelectrical control means is provided so as to cause the cutter to moveon thejointline by the output of an electrical operational-mechanismhaving an electrical automatic servo-circuit which includes the-radiusof each pipe andthe joint angle as theoperational factors, and whichsets the tunctionof the rotating angle of one of the pipes in accordancewith the function of the rotational angle of the other pipe therebycausing the joint line to he converted *to the function of the distancein the axial direction corresponding to the rotational angle'ot the pipeto be worked. Therefore, accurate cutting can be accomplished byautomatically controlling the position of the cutter :by settingnecessary operational :factors in accordance with the shape of the jointline of the pipes, Furthermore, according to this invention, since thecontrol is carried out by means of a purely electrical servooperationalmechanism, setting operation becomes very easy and control errorsbecomes few in addition to simplicity of structure, without requiringlevers or the like as operational means.

Since it is obvious that many changes and modifications can be made inthe above described details without departing from the nature and spiritof the invention, it is to be understood that the. invention is not tobe limited to the details described herein except as set forth in theappended claims. i

What is claimed is: j

1. An automatic pipe cutting apparatus wherein pipes to be joined areout along the joint line thereof, comprising a supporting means forsupporting and rotating a pipe to be cut and worked, a cutting meanssupported at an appropriate angle with respect to said pipe, anelectrical operational mechanism adapted to move said cutting meansalong a path parallel to the axis of said pipe on th Side center linethereof, means to convert radii (r, R)

Off said two pipes to be joinedirrto respective electrical quantities,an electrical servo-operational device to cs tablish a relation, that isv v the electrical quantity representing the radius (r) of one pipecosine of the rotational angle (wt) of said pipe n i :electricalquantity representing the radius (R) of the other pipe X cosine of therotational angle (a) of said other pipe, I

an amplifier circuit (A to calculate an equation of the electricquantity representing the radius (r) or" one pipexa trigonometricalfunction of the rotational angle (wt) of said onjpipe+ p the electricalquantity representing the radius (R) of said other pipeX'trigonometrical function of the ro- 'taitional angle (or) of saidother pipextrigonomet rical 'iunctionof an angle (6) between said twopipes and mean energized *by the output'fro'rnsaid amplifier circuit (Ato cut and work said pipes.

2. An automatic pipe cutting apparatus wherein pipes to be joined areout along the joint line thereo f, comprising'a supporting means forsupporting and rotating a pipe to be cutand worked, a cutting meanssupported at an appropirate angle with respect to said pipe, "anelectrical operational mechanism adapted to move said cutting meansalong a path parallel' to theaxis "of said pipe on theside center linethereof,.means to convert radii (r, R) of said two pipes to be joinedintorespective electrical quantities, "an electrical servo operationaldevice to es tablish a relation, that is I the electrical quantityrepresenting the radius (r) of one pipe sine of the rotational angle(wt) of said pipe =electrical quantity representing the radius (R) ofthe other pipexsine of the rotational angle (a) of said otlier pipe, anamplifier circuit (A to calculate an equation of I :the electricquantity representing the radius (r) of one pipexa trigonometricalfunction of the rotational angle (wt) of saidone pipe+. the electricalquantity representing the radius (R) of said other pipe Xtrigonometrical function of the rotational angle (or) of said otherpipextrigono metrical function of an angle ('6) between said two pipesand means energized by the output from said amplifier circuit (A to outand work said pipes.

References Cited UNITED STATES PATENTS 6/1934 TWeit 26623O 3/1961 Werner-Q 266230

1. AN AUTOMATIC PIPE CUTTING APPARTUS WHEREIN PIPES TO BE JOINED ARE CUT ALONG THE JOINT LINE THEREOF, COMPRISING A SUPPORTING MEANS FOR SUPPORTING AND ROTATING A PIPE TO BE CUT AND WORKED, A CUTTING MEANS SUPPORTED AT AN APPROPRIATE ANGLE WITH RESPECT TO SAID PIPE, AN ELECTRICAL OPERATIONAL MECHANISM ADAPTED TO MOVE SAID CUTTING MEANS ALONG A PATH PARALLEL TO THE AXIS OF SAID PIPE ON THE SIDE CENTER LINE THEREOF, MEANS TO CONVERT RADII (R, R) OF SAID TWO PIPES TO BE JOINED INTO RESPECTIVE ELECTRICAL QUANTITIES, AN ELECTRICAL SERVO-OPERATIONAL DEVICE TO ESTABLISH A RELATION, THAT IS. THE ELECTRICAL QUANTITY REPRESENTING THE RADIUS (R) OF ONE PIPE X COSINE OF THE ROTATIONAL ANGLE (WT) OF SAID PIPE =ELECTRICAL QUANTITY REPRESENTING THE RADIUS (R) OF THE OTHER PIPE X COSINE OF THE ROTATIONAL ANGLE (A) OF SAID OTHER PIPE, 